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Title: Groundwater flow and solute movement to drain laterals, western San Joaquin Valley, California. 1. Geochemical assessment

Book ·
OSTI ID:7161516
;  [1]
  1. Geological Survey, Sacramento, CA (United States)

A study was undertaken to quantitatively evaluate the hydrologic processes affecting the chemical and isotopic composition of drain lateral water from an agricultural field in the western San Joaquin Valley, California. Results from chemical and isotopic analysis of the samples, and analysis of hydraulic head data and drain lateral flow data, elucidate the process of mixing of deep and shallow groundwater entering the drain laterals. The deep groundwater was subject to partial evaporation prior to drainage system installation and has been displaced downward in the groundwater system. This groundwater is flowing toward the drain laterals. The percentage of deep, isotopically enriched groundwater entering the drain laterals varies with time and between drain laterals. The percentage of the total drain lateral flow, which is deep groundwater flow, is about 30% for the shallow drain lateral and 60% for the deep drain lateral. During irrigation, these percentages decrease to 0 and 30% for the shallow and deep drain laterals. Selenium loads in the drain laterals vary with time and between drain laterals. The selenium load for the shallow drain lateral during 1 year is 21% of the load for the deep drain lateral because it collects less deep, high selenium groundwater and does not flow continuously. Although selenium concentrations in the drain lateral water decreased during irrigation, selenium loads increased substantially during a preplant irrigation because of increased flow into the drain laterals. The selenium loads during 8 days of irrigation represented a substantial percentage of the total selenium load for 1 year.

OSTI ID:
7161516
Resource Relation:
Related Information: Open-File Report 90-136
Country of Publication:
United States
Language:
English